Crossword Genius

Under Control' playing (a bit of a racket) (2,1,6)

Ross

I believe the answer is:

on a string

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'under control'' is the definition.
(I've seen this before)

'playing a bit of a racket' is the wordplay.
'playing' becomes 'on' (on can mean playing or performing).
'bit of a racket' becomes 'string' (I can't explain this - if you can you should give a lot more credence to this answer).
'on'+'a'+'string'='ON A STRING'

Can you help me to learn more?

(Other definitions for on a string that I've seen before include "under one's control" , "Pearl may be" , "under complete control" , "left dangling?" , "Yo-yo is" .)

I've seen this clue in The Independent.
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